GUI text entry tkinter

[v13tn1g]

so basically my GUI window has 4 text entries where the user inputs stuff. i have created a clear button with in my window, the thing that i was wondering is how do i create a function to associate with the clear button to clear all text entries entered by the user?.

thanks

[boxfish]

I haven't written a Tkinter program for a while, but it looks like you can clear a text entry like this:

myEntry.delete(0, END)

Is that what you're looking for?

[v13tn1g]

for some reason that isnt working for me...

def evClear():
    q1_data.delete(0,END)
    q2_data.delete(0,END)
    q3_data.delete(0,END)
    q3_data2.delete(0,END)
 
 
def quit(window):
    window.destroy()
 
def run_analyse(db):
    window = Tk()
 
 
    frame = Frame(window)
    frame.pack()
 
    q1_prompt = Label(frame, text="Enter a series:")
    q1_prompt.grid(row=0, column=0)
    q1_data= Entry(frame)
    q1_data.grid(row=0, column=1)
 
    q2_prompt = Label(frame, text="Enter an element:")
    q2_prompt.grid(row=2, column=0)
    q2_data = Entry(frame)
    q2_data.grid(row=2, column=1)
 
    q3_prompt = Label(frame, text="Enter the first element:")
    q3_prompt.grid(row=4, column=0)
    q3_data = Entry(frame)
    q3_data.grid(row=4, column=1)   
    q3_prompt2 = Label(frame, text="Enter the second element:")
    q3_prompt2.grid(row=5, column=0)
    q3_data2 = Entry(frame)
    q3_data2.grid(row=5, column=1)
 
    b1 = Button(frame, text = "Enter")
    b1.grid(row=6, column=1)
 
    quit_button = lambda : quit(window)
    b2 = Button(frame, text = "Quit", command = quit_button)
    b2.grid(row=8, column=1)
 
 
    bClear = Button(frame, text="Clear", command = evClear)
    bClear.grid(row=7, column=1)
 
 
    window.mainloop()
 
 
 

for some reason it doesnt clear the entries....it says that they are not defined...such as q1_data is not defined...but it is :s can you debug this?

thanks

[boxfish]

The text entries are global variables, so evClear is not allowed to access them unless you explicitly say so. Use the global keyword:

def evClear():
    global q1_data, q2_data, q3_data, q3_data2
    q1_data.delete(0,END)
    q2_data.delete(0,END)
    q3_data.delete(0,END)
    q3_data2.delete(0,END)
 

I hope this helps.

[v13tn1g]

@boxfish
ahh thanks boxfish!!

[boxfish]

You're welcome, glad it worked.

[v13tn1g]

hmm acutally inputting that code didn't work :s, it still says q1_data is not defined

[bvdet]

Try making the global declaration inside function run_analyse(db).

-BV

[boxfish]

@bvdet
Wow, that works! That really baffles me. What is the global statement doing? Is it actually turning them into global variables? I thought the global statement only made variables available for the function that used it. I definitely learned something today.

[bvdet]

When Python resolves an identifier, it first checks the local namespace, then checks the global namespace, and then checks the __builtins__ namespace before raising a NameError exception. The global namespace for a function is always the module in which the function is defined.

[v13tn1g]

@bvdet
how would i do that?..i've never learnt about global before..:s

[bvdet]

Add the following statement inside the body of function run_analyse(db) after the names have been assigned an object.

global q1_data, q2_data, q3_data, q3_data2

[v13tn1g]

hahha thanks bvdet it works perfectly!! btw i had to add it before the names were mentioned.

[bvdet]

v13tn1g,

I am pleased it works for you. Yes, the global declaration must be made before the assignment. I have not used global in years, and I forgot the proper syntax.